HELCOM RED LIST Biotope Expert Team
photic zone bottoms with at least 90 % coverage of muddy sediment. The sediment
must contain at least 20 % of mud, silt or clay (grain size less than
63 µm). Biomass of infaunal bivalves dominates and is highest in the group
that includes infaunal bivalves/polychaetes/crustaceans/echinoderms/insect
larvae. Out of the infaunal bivalves ocean quahog (Arctica islandica)
constitutes at least 50 % of the biomass.
is muddy sediment. Appears in low to moderate energy exposure classes.
abundance and biomass of fauna.
2.7 Muddy bottoms
2.7.2 Sublittoral photic zone
220.127.116.11 With little or no macrophyte vegetation
A5 Sublittoral sediment
A5.3 Sublittoral mud
A5.31 Sublittoral mud in low or reduced salinity
A5.311 Baltic brackish water sublittoral muddy biocenoses influenced by
This biotope has been listed as Near Threatened (NT) in the HELCOM Red List of Baltic Sea biotopes and habitats.